Analiza naprezanja u stupu vjetroagregata

Ivasović, Benjamin (2015) Analiza naprezanja u stupu vjetroagregata. = Stress analysis in wind turbine tower. Undergraduate thesis , Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, UNSPECIFIED. Mentor: Jarak, Tomislav.

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Abstract (Croatian)

U ovom završnom radu provedena je kvazistatička analiza čvrstoće stupa prototipa vjetroagregata s horizontalnom osi vrtnje K80 snage 2,5 MW tvrtke Končar. Stup je izrađen od čelika. Stup je sastavljen od segmenata cilindričnog i konusnog oblika. Stup se sastoji od četiri segmenta međusobno spojenih vijcima. Opterećenje stupa izračunato je u programskom paketu Bladed, prema Germanischer Lloyd smjernicama za klasu IIA vjetroagregata. Analiza čvrstoće provedena je numerički u programskom paketu Abaqus primjenom metode konačnih elemenata. Proračunski model vjetroagregata sastoji se od deset različitih dijelova. Šest dijelova koji predstavljaju prirubnice modelirano je kao standardna trodimenzijska tijela, a ostali dijelovi kao ljuske. Dijelovi su nakon spajanja u sklop diskretizirani mrežom tetraedarskih, prizmatičnih i pravokutnih ljuskastih konačnih elemenata. Stup vjetroagregata bilo je potrebno opteretiti vlastitom težinom, vjetrom, silama i momentima na vrhu stupa koji su posljedica dijelova koje stup nosi. Detaljno je analizirano opterećenje stupa uslijed djelovanja vjetra, pri čemu je opterećenje od djelovanja vjetra modelirano kao površinsko opterećenje na vanjsku površinu stupa. Za modeliranje služilo se smjernicama iz „Eurocode 1: Actions on structures — General actions — Part 1-4: Wind actions“. Također je u radu korištena tehnika podmodeliranja, da bi gustom mrežom konačnih elemenata diskretizirali dio oko ulaza u stup vjetroagregata gdje se očekuje pojava koncentracije naprezanja zbog složene geometrije. Prije numeričke analize stupa vjetroagregata K80, izvršena je verifikacija korištenih konačnih elemenata na problemu savijanja cilindra opterećenog vlastitom težinom i hidrostatskim tlakom. Kao rubni uvjet na donjem kraju cilindra definirano je uklještenje. Iz rezultata dobivenih proračunom zaključeno je da postojeća konstrukcija stupa zadovoljava kriterij čvrstoće za razmatrani slučaj opterećenja koji odgovara opterećenju pri normalnoj proizvodnji struje uz gubitak električne mreže pri ekstremnim udarima vjetra koji se javljaju jednom godišnje.

Abstract

This paper describes a quasi-static stress analysis of the wind turbine tower prototype K80 with horizontal axis of rotation and 2.5 MW of power manufactured by Končar. The tower is built of steel. The tower is assembled from segments which have cylindrical or conical shape. The tower consists of four segments, mutually combined with screws. The tower load is calculated for IIA class wind turbine, according to Germanischer Lloyd guidelines for wind turbines design, using the Bladed software. The numerical stress analysis is conducted in Abaqus software, using Finite Elements Method. The wind turbine calculation model is composed of ten various parts. Six parts that represents flanges are Solid modeled and rest of them are Shell modeled. After connecting the assembly, the parts are discretized using a mesh composed of tetrahedral, prismatic and rectangular shell finite elements. It was necessary to load the wind turbine tower with its own weight, the wind load, and concentrated forces and moments acting at the top of the tower that are result of parts carried by the tower. The load from the wind is detailed analyzed, while the load from the wind to the tower is modeled as a surface load to the outer surface of the tower. For modeling, the guidelines from „Eurocode 1: Actions on structures — General actions — Part 1-4: Wind actions“ are used. The submodeling technique is used for making dense mash of finite elements in the region of the entrance to the tower where the stress concentration, due to complex geometry, is expected. Prior to the numerical analysis of wind turbine tower K80, the verification of applied elements performed for solving the problem of a cylinder loaded by its own weight and hydrostatic pressure. Thereby, the encastre boundary condition is defined for the lower end of the cylinder. From the calculation results, it has been concluded that the existing construction of the tower satisfies the stress criterion for the load case considered. The analyzed load case corresponds to the load generated during the normal electricity production, coupled with the loss of electrical network at extreme wind gusts, which appear once a year.

Item Type: Thesis (Undergraduate thesis)
Uncontrolled Keywords: vjetroagregat; stup; opterećenje vjetrom; analiza čvrstoće; metoda konačnih elemenata; numerička analiza;
Keywords (Croatian): wind turbine; tower; wind load; strength analysis; finite elements method; numerical analysis;
Subjects: TECHNICAL SCIENCE > Mechanical Engineering > general mechanical engineering (construction)
Divisions: 200 Department of Engineering Mechanics > 210 Chair of Mechanics and Strength of Materials
Date Deposited: 26 Feb 2015 09:45
Last Modified: 14 Apr 2020 14:59
URI: http://repozitorij.fsb.hr/id/eprint/3229

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